We report on the discovery of an apparent triple radio structure hidden inside the radio bubble of the ultraluminous X-ray source Holmberg II X-1. The morphology is consistent with a collimated jet structure, which is observed to emit optically thin synchrotron radiation. The central component has a steep radio spectrum and is brighter than the outer components indicating a renewed radio activity.We estimate a minimum time-averaged jet power of ~2 × 1039 erg s-1 that is associated with a time-averaged isotropic X-ray luminosity of at least 4 × 1039 erg s-1. Our results suggest that Holmberg II X-1 is powered by a black hole of MBH ≥ 25 M⊙, that is inferred to be accreting at a high Eddington rate with intermittent radio activity. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
CITATION STYLE
Cseh, D., Kaaret, P., Corbel, S., Grisé, F., Lang, C., Körding, E., … Frey, S. (2014). Unveiling recurrent jets of the ULX holmberg II X-1: Evidence for a massive stellar-mass black hole? Monthly Notices of the Royal Astronomical Society: Letters, 439(1). https://doi.org/10.1093/mnrasl/slt166
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